Vernier drive



May 14, 1929. E R055 1,713,194

VERNI ER DRIVE Fild Deo. 27, 1924 I' "lll/1111111 www i Z7 Inventor: T-Ernest Ross,

2f by M His Attorney.

Patented May 14, 1929.

UNITED STATES l 1,713,194 PATENT' oFElcE.

EENEsr Eoss, or NEWARK, NEW JERSEY, AssIaNoE 'ro GENERAL ELECTRIC con-PANL A coEroEATIoN or NEW Yoan.

VEBNIER DRIVE.

Application led December 27, 1924. Serial No. 758,475.

My present invention relates to a driving apparatus whereby a movementof a driving member produces a relatively smaller movement of a drivenmember, and more particu- `:s larly to so-called Vernier drive apparatussuch as is frequently employed for accurate tuning of electric circuits.

The object of my invention is to provide an apparatus of the classdescribed which will be simple in its construction and positive in itsaction for driving a rotating member in either directionand which at thesame time will permit of any desired reduction in speed between thedriving membe` and the member to be driven.

The novel features which I believe to be characteristic of my inventionare set forth/ with particular-ity in the appended claim. My invention,itself, however bot-h as to its organization and method of operationwill best be understood by reference to the following description taken'in connection with the accompanying drawing inwhich Fig. 1 is asectional view of an apparatus embodying my invention; Fig. 2 is an endview of the driving portion thereof; Fig. 3 is a diagrammaticrepresentation of a portion of the driving mechanism to illustrate theprinciple of the operation thereof; Fig. 4 yis a sectional View of amodified form of my invention and Fig. 5 is a diagrammaticrepresentation of the driving mechanism of the form of my inventionshown in Fig. 4.

I have indicated in Fig. 1 the application of my invention to a variablecondenser of the general type commonly used in radio communication orfor similar purposes. This comprises a series of stationary nlates 1which are secured in a frame work comprising end members 2 and 3 bymeans of a screw-bolt 4.

The rotating plates 5 of the condenser are mounted upon a hollow shaft 6being suitably spaced by means of spacing blocks 7 and secured by meansof a nut 8. Extending through the hollow shaft 6 is a driving shaft 9having at its end the usual operating knob 10. The rotating member ofthe condenser is associated with driving shaft 9 through the medium of aplurality of balls 11. I have indicated in the drawing three of theseballs though, of course, a greater number may be employed if desired.Balls 11 are retained between two concentric races, the outer race 12 issecured to a member `13 which in turn is secured by means of nut 14 tothe driving shaft 9. The inner race Which'is in the form of a groove ismade up of two part-s. The part 15 is secured to the end piece 3 of thecondenser by means of a nut 16. The second part 17, of the inner race isadjustable in .order that the balls may be in good contact with bothraces at all times. The spring 18 which is located between the part ,17and the end piece 3 of the condenser provides for the desired adjustmentof the part 17.'

A retainer 19 in the form of a cylindrical member, having slots 20` cutthereln for receiving the balls 11, is secured to the end of the hollowshaft 6.

yWhen the shaft 9 is rotated the outer race 12 is rotated therewith andthis causes the balls l11 to rotate. At the same time the balls movecircumferentially in the groove which constitutes the inner race. Itwill be noted that the two sides of the inner race are inclined towardone' another at an angle, indicated in Fig'.` 3 as a soy that the ballsmake contact with the two sides of the groove at points 21 which areconnected less than 180 apart along the circumference of the balls. As aresult each ball rotates with respect to the outer race around a radiusequal to the radius of the ball but it rotates with respect to the innerrace around a radius equal to the distance indicated on the drawing bythe a. As a result when the outer race moves a distance equal to thecircumference of the ball, the ball travels cireumferentially along theinner'race a distance only equal'to the circumference of a circle havingradius a. By suitable selection of the angle of inclinationa thisdistance may be made materially less than the distance of travel of theouter race' 12. That is, the smaller angle a isl made, the greater willbe the ratiojbetween the distances traveled by the outer race and by theballs along the inner race. As the balls i travel circumferentially inthe inner race, they carry with them the retainer 19 and thus impartmotion to the driven shaft 6.

In the modification shown in Fig. 4 of the drawing, the same principleis employed in a slightly different way. In this case the knob 10 isattached to a short driving shaft 6', the end .of which carries innerrace 22. vA ball retainer 23 which is of similar form to that shown inFig. 1 is secured to the end of the shaft 24 which carries the movableplates 5 of the condenser. In this case the outer race a good contactwith the two races.

25 ismade up in the same way as the inner race of the modification shownin Fig.` 1, a sprinfr 26 serving to adjust the movable portion 2?? oftheouter race to keep the balls in The ratio between the distances oftravel of the driving member and the member driven in this case, as inthe form shown in Fig. 1, depends upon the angle oc A greater ratio inspeed reduction however may be obtained with this form because of thefact that the circumference of the race carried by the driving member ismuch less than in the form shown in Fig. 1. Hence other dimensions beingsimilar, one turn of the knob in the form shown in Fig. 4 will .producea much smaller movement of lie driven member than in the form shown inim l.

Vhile I have shown and described the preferred embodiments of myinvention, it will be apparent that many modifications may be -made inthe structure and arrangement of the various parts used as well as inthe practical application of my invention without departing from thescope thereof as set forth in lVhat I claim as new and desire to secureby Letters Patent of the United States, is:

A wireless apparatus comprising afrotatable driven sha t, a' panelthrough which said shaft extends, an indicator member, adjustable meansfor said shaft, said means comprising an internal friction gear having aknob attached thereto, a stationary friction gear concentric with saidinternal gear, a

plurality of balls interposed between said

